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Fix Cloudflare Error 521 on Apache Server - How to Fix Error 0x80073712 Without Resetting Your PC-Fix Windows Defender Proxy Error on Windows 11

Updated 2026-06-13 16:06:48cloud-software
Fix Cloudflare Error 521 on Apache Server - How to Fix Error 0x80073712 Without Resetting Your PC-Fix Windows Defender Proxy Error on Windows 11
Likely symptom
Likely cause
Safe rollback

Verification route

  • Repeat the original action, not only a simplified test case.
  • Restart the app or reload the service after configuration changes.